| Voigt function fit using MPFIT [message #86086] |
Wed, 02 October 2013 04:12  |
Sreelakshmi S
Messages: 8
Registered: April 2013
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Junior Member |
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Hi,
I have a set of observed data of flux vs wavelength.I am trying MPFIT to fit a voigt function. I defined the function as
FUNCTION fit,p,X=x2,Y=nflux2
model=double((voigt(p[0],p[1])*1e-13)/(p[3]*sqrt(!pi)))
return,(Y-model)/err
END
But when I run this, the following errors are coming
FUNCTION fit,x2=X,nflux2=Y,p
^
% Programs can't be compiled from single statement mode.
return,(Y-model)/1
^
% Syntax error.
Why is this happening?
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| Re: Voigt function fit using MPFIT [message #86089 is a reply to message #86086] |
Wed, 02 October 2013 05:47  |
Helder Marchetto
Messages: 520
Registered: November 2011
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Senior Member |
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On Wednesday, October 2, 2013 1:12:55 PM UTC+2, Sreelakshmi S wrote:
> Hi,
>
>
>
> I have a set of observed data of flux vs wavelength.I am trying MPFIT to fit a voigt function. I defined the function as
>
>
>
> FUNCTION fit,p,X=x2,Y=nflux2
>
>
>
> model=double((voigt(p[0],p[1])*1e-13)/(p[3]*sqrt(!pi)))
>
> return,(Y-model)/err
>
>
>
> END
>
>
>
> But when I run this, the following errors are coming
>
>
>
> FUNCTION fit,x2=X,nflux2=Y,p
>
> ^
>
> % Programs can't be compiled from single statement mode.
>
>
>
>
>
> return,(Y-model)/1
>
> ^
>
> % Syntax error.
>
>
>
> Why is this happening?
Well, there are a number of things wrong.
1) If you define the function with
FUNCTION Fit, Y=nFlux2
then you must use nFlux2 in your code, not Y.
Try making a function like this:
FUNCTION Fit, Y=nFlux2
PRINT, (N_ELEMENTS(Y) NE 0)?'Y Exist':'Y does not exist'
PRINT, (N_ELEMENTS(nFlux2) NE 0)?'nFlux2 Exist':'nFlux2 does not exist'
RETURN, ''
END
and look at the result of the following commands:
print, Fit(Y=5)
print, Fit(/Y)
print, Fit()
print, Fit(nFlux2=5)
This way you should learn something about passing variables.
2) How are you calling the function? I have the feeling that this is not happening from inside another program or from within IDL.
3) Are you sure there is no other function named fit? The first line of the function you wrote and the one showed are different.
4) In your Voigt function you use parameters p[0], p[1], p[3]. Is there a reason for skipping [2]?
5) The variable "err" is not defined in the function. This will for sure through an error. (well what should an err variable do anyway!)
6) Passing two scalar values to the function will return a scalar value. Is that what you want? I don't think so...
7) I think that the NASA library has some Voigt fit functions... did you look at those?
Regards,
Helder
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| Re: Voigt function fit using MPFIT [message #86115 is a reply to message #86086] |
Mon, 07 October 2013 18:39 |
Sreelakshmi S
Messages: 8
Registered: April 2013
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Junior Member |
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On Wednesday, October 2, 2013 4:42:55 PM UTC+5:30, Sreelakshmi S wrote:
> Hi,
>
>
>
> I have a set of observed data of flux vs wavelength.I am trying MPFIT to fit a voigt function. I defined the function as
>
>
>
> FUNCTION fit,p,X=x2,Y=nflux2
>
>
>
> model=double((voigt(p[0],p[1])*1e-13)/(p[3]*sqrt(!pi)))
>
> return,(Y-model)/err
>
>
>
> END
>
>
>
> But when I run this, the following errors are coming
>
>
>
> FUNCTION fit,x2=X,nflux2=Y,p
>
> ^
>
> % Programs can't be compiled from single statement mode.
>
>
>
>
>
> return,(Y-model)/1
>
> ^
>
> % Syntax error.
>
>
>
> Why is this happening?
Hi,
Thank you for your inputs.
I have modified the function as
FUNCTION voigtfit,p,x,y,er
lambda1=1025.7230
gamma1=1.897e08
f1=2.638e-2
av1=double((gamma1*lambda1*1e-13)/(4*!pi*p[0]))
u1=(y/p[0])-(p[1]/p[0])
dop1=double(p[0]/lambda1)
phi1=double((voigt(av1,u1)*1e-13)/(dop1*sqrt(!pi)))
tau1=double(2.654e-02*p[2]*f1*phi1)
model1=double(exp(-tau1))
return,(y-model1)/er
END
and I am calling this function from IDL as below
fac={X:vel,Y:nflux2,ERR:dy}
result=double(mpfit('voigtfit',p,functargs=fac))
Now when I run this an error comes
% MPFIT: Error detected while calling voigtfit:
% MPFIT:Keyword parameter not allowed in call.
% MPFIT: Error condition detected. Returning to main level.
Which is the keyword here? What is this error?
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| Re: Voigt function fit using MPFIT [message #86118 is a reply to message #86115] |
Tue, 08 October 2013 11:14 |
Mats Löfdahl
Messages: 263
Registered: January 2012
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Senior Member |
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On 2013-10-08 03:39, Sreelakshmi S wrote:
> On Wednesday, October 2, 2013 4:42:55 PM UTC+5:30, Sreelakshmi S wrote:
>> Hi,
>>
>>
>>
>> I have a set of observed data of flux vs wavelength.I am trying MPFIT to fit a voigt function. I defined the function as
>>
>>
>>
>> FUNCTION fit,p,X=x2,Y=nflux2
>>
>>
>>
>> model=double((voigt(p[0],p[1])*1e-13)/(p[3]*sqrt(!pi)))
>>
>> return,(Y-model)/err
>>
>>
>>
>> END
>>
>>
>>
>> But when I run this, the following errors are coming
>>
>>
>>
>> FUNCTION fit,x2=X,nflux2=Y,p
>>
>> ^
>>
>> % Programs can't be compiled from single statement mode.
>>
>>
>>
>>
>>
>> return,(Y-model)/1
>>
>> ^
>>
>> % Syntax error.
>>
>>
>>
>> Why is this happening?
>
> Hi,
> Thank you for your inputs.
> I have modified the function as
>
> FUNCTION voigtfit,p,x,y,er
>
> lambda1=1025.7230
> gamma1=1.897e08
> f1=2.638e-2
>
> av1=double((gamma1*lambda1*1e-13)/(4*!pi*p[0]))
> u1=(y/p[0])-(p[1]/p[0])
> dop1=double(p[0]/lambda1)
>
> phi1=double((voigt(av1,u1)*1e-13)/(dop1*sqrt(!pi)))
> tau1=double(2.654e-02*p[2]*f1*phi1)
> model1=double(exp(-tau1))
> return,(y-model1)/er
> END
>
> and I am calling this function from IDL as below
>
> fac={X:vel,Y:nflux2,ERR:dy}
> result=double(mpfit('voigtfit',p,functargs=fac))
>
> Now when I run this an error comes
> % MPFIT: Error detected while calling voigtfit:
> % MPFIT:Keyword parameter not allowed in call.
> % MPFIT: Error condition detected. Returning to main level.
>
> Which is the keyword here? What is this error?
There are instructions at the beginning of mpfit.pro. They say how the
function voightfit (or myfunct, as it is called there) should be
defined. It should have a single non-keyword parameter only, the
parameter list P. All other parameters must be keyword parameters,
corresponding to the parameter list in functargs.
So you need something like
FUNCTION voigtfit,p,x=x,y=y,er=er
The reason you get a "keyword parameter not allowed in call" is that
mpfit tries to call voigtfit with the keyword parameters you specified
by defining fac the way you did and giving it to mpfit through the
functargs keyword.
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